1. Field of the Disclosure
The present disclosure relates to an image forming apparatus that does not have paper jams or toner splatter in a case of a paper size designated by a user and the size of paper fed differing.
2. Related Art
Conventionally, in an image forming apparatus having multiple functions, in a case of the image forming apparatus functioning as a printer, for example, information of the size of the recording paper to be used is included as a part of the image information from a personal computer. In addition, in a case of the image forming apparatus functioning as a photocopier, for example, the paper size is detected automatically by a predetermined sensor or the like.
Herein, in the case that a simplified image forming apparatus does not have a function of automatically detecting the size of recording paper, the image forming apparatus acquires the size information of the recording paper through a dial control or the like for size designation from the user.
However, in this case, if the user makes a mistake in a manual input, a case may arise in which the size of recording paper detected by the image forming apparatus control unit and the size of recording paper actually fed to the image forming unit differ.
In addition, in a case such that recording paper size to be fed from a manual feed tray 21 (refer to FIG. 1) changes variously, the size of recording paper recognized by the image forming apparatus control unit and the size of recording paper actually fed to the image forming unit may similarly differ due to error in operation of the manual feed tray or the like.
In such a case, for example, if the size of the image attempted to be printed is larger than the size of the recording paper actually fed, and image formation onto a photoconductor 1 is carried out as is, a portion of the toner image not transferred to the recording paper will remain on the photoconductor 1. In this case, the residual toner may splatter inside of a multifunction peripheral X1 or monochrome printer X2, and contaminate the inside of the device.
In addition, in a case of the size of the image attempted to be printed being smaller than the size of the recording paper actually fed, the image will be formed only on a portion of the recording paper, resulting in a misprint.
In contrast, an image forming apparatus is known that is easy for a user to decide that setting to continue or stop an image forming operation when there is a paper size inconsistency is performed by a user based not only on a consistency/inconsistency between the paper size detected and the designated paper size.
This image forming apparatus detects the size of recording paper fed, compares this detected paper size with the designated paper size thus designated, and in the case of there being an inconsistency between the two paper sizes, detects this as a paper size error. The user sets in advance whether or not to ignore this paper size inconsistency. When a setting is made to ignore the paper size inconsistency during the detection of a paper size error, the image forming operation continues, and when a setting is not made to ignore the paper size inconsistency, the image forming operation is interrupted. Then, when the paper size inconsistency is ignored and the image forming operation is continued, processing is performed to set the throughput of image formation to match the longer one among the feed-direction length of the detected paper size and the paper feed-direction length of the designated paper size.
Then, in this image forming apparatus, a registration sensor S2 is used that measures the size of the recording paper, and is provided just before the registration roller 28 in order to measure the timing at which to feed recording paper into the image forming unit.
However, the aforementioned such registration sensor S2 is provided just before the registration roller 28 feeding recording paper into a transfer unit; therefore, the moment at which the size of the recording paper is detected by the registration sensor S2 is after a majority of image formation has already been executed, and the transfer of excess toner to the intermediate transfer belt or photoconductor cannot be prevented even if stopping the image forming operation at this moment.
Therefore, with this image forming apparatus, the scattering of toner due to a mistake in the setting of the paper size cannot be prevented.
In addition, although the user sets in advance whether or not to ignore a paper size inconsistency in this image forming apparatus, the impact is completely different depending on which among the size set by the user for the paper size as previously described and the size of the recording paper actually fed is actually larger; therefore, a case will arise in which contamination from toner inside of the device cannot actually be prevented if whether or not to ignore is set in advance.
In addition, in order to eliminate such an inconvenience, a device also actually exists that normally causes the feed of recording paper to stop and forcibly brings about a paper jam in a case of an inconsistency in the recording paper size having been detected. However, in this case, every time an inconsistency in the size of the recording paper occurs, the user must deal with the paper jam, and thus the burden on the user will be great.